Paper making machines employing head boxes not of the variable deckle type always generate trim which proceeds to a couch pit for subsequent recovery and recycling through the machine.
It is known to provide knock-off showers for removing trim from a Fourdrinier wire or other paper web forming fabrics as well as for cleaning the fabric. The width of the trim being removed from the wet paper web varies depending upon a number of factors. However, prior art knock-off showers utilized to remove trim deliver the same amount of water and over the same wire area for such purpose regardless of the width of the trim being removed. This can cause a variety of problems downstream during the recovery process.
In the recovery process, excess water from the couch pit must be removed to raise consistency before the trim can be recirculated through the paper making machine. This problem is aggravated considerably when a relatively narrow strip of trim is being knocked off the forming wire since prior art systems emit water from all of the nozzles thereof regardless of trim width.
A search of the prior art located the following United States patents which are believed representative of the current state of the prior art: U.S. Pat. No. 4,154,648, issued May 15, 1979, U.S. Pat. No. 3,218,227, issued Nov. 16, 1965, U.S. Pat. No. 5,045,154, issued Sep. 3, 1991, U.S. Pat. No. 3,245,872, issued Apr. 12, 1966, U.S. Pat. No. 3,839,148, issued Oct. 1, 1974, U.S. Pat. No. 5,234,172, issued Aug. 10, 1993, U.S. Pat. No. 4,897,159, issued Jan. 30, 1990, U.S. Pat. No. 4,701,242, issued Oct. 20, 1987, and U.S. Pat. No. 4,390,433, issued Jun. 28, 1983.
None of these patents illustrate an arrangement for varying the quantity of water or other liquid applied to remove paper web trim from a forming wire to compensate for different trim widths.